Various compressed air foam systems (CAFS) have been used in firefighting applications for some time. In its most basic form, a CAFS is simply a means for mixing air and water with a surfactant in order to produce a water-based foam that is used to extinguish fires. A CAFS provides quicker “knockdown” against potent fires, deeper penetration of fuels, and gives firefighters the advantage of making their initial attack against a fire from a significantly greater distance than with a traditional water stream or fog pattern. The bubble structure allows for greater expansion of delivered water surface area, allowing for greater heat reduction compared to equal amounts of plain water. Foam blankets allow for pre-treatment of fuels that are not already involved in the fire, and have less adverse impact on property, as well as helping to prevent damage to evidence used for fire investigations. In fact, some studies have indicated that CAFS increases the effectiveness of water as an extinguishing agent by approximately a factor of five. CAFS may be particularly valuable for rural fire departments, because the use of foam reduces the amount of water required to extinguish a fire, and rural departments are often quite limited in the amount of water that they have available at any particular fire.
A typical CAFS allows for the manipulation of the ratio of liquid to air that is mixed to produce the CAFS flow. Different consistencies of foams have proven superior or inferior for different firefighting applications. The foams thus produced may vary from a “dry” foam with a consistency similar to shaving cream, to a “wet” foam that is of a consistency more similar to a runny semi-liquid. In addition, there may be certain applications where it is more desirable to provide a stream of solution (water and surfactant) without the introduction of air that would produce a foam. A solution stream has been shown to be more effective than simple water in suppressing certain types of fires, and there are firefighting applications where such a solution stream is deemed more desirable than the use of CAFS foams.
While the ability to control the mixing ratio of water to air is thus desirable, existing systems that allow a firefighter to control this mixing ratio suffer from a number of disadvantages. Typically, the valve used in a CAFS is a standard, quarter-turn ball valve. This type of valve does not increase or decrease water flow in a manner that is proportional to the degree of rotation of the valve handle. For example, turning the ball valve one-half of the way from the fully closed to the fully open position (i.e., a one-eighth of a circle turn) does not represent a flow rate that is one-half of the fully open valve flow rate. Thus a firefighter cannot judge the rate of flow for the water that is being delivered simply by gauging the lever position as a linear indication of the degree of rotation of the ball valve. It would thus be desirable to provide a control mechanism to the firefighter operating a CAFS that would provide an easily and quickly understood indicator of the volume of flow being provided for mixing in the CAFS.
Another limitation of existing CAFS control systems is that they are difficult to read in the conditions often encountered by firefighters. A standard gauge, for example, may be used to indicate flow levels, but it may be difficult for a firefighter in the context of fighting a fire to read these gauges. Various conditions, such as darkness, rain or snow, heavy smoke, fog, and other difficult conditions often encountered by firefighters exacerbate this problem. It would be desirable to provide a high visibility, easily and quickly read control system and mixing indicator that allows a firefighter to quickly and accurately manipulate CAFS mixing and flow during even the most difficult firefighting conditions. Such a system would allow the operator to turn the control valve to a position and know the quality of foam that will be produced, without the necessity of checking the resulting stream and making adjustments based on the observed results. Such a system would also desirably include an easily and quickly readable output display to indicate CAFS quality to the operator during use.
The art includes scrolling light feedback displays for certain firefighting purposes. For example, the Hale Class 1 ITL-40 display is intended to be used to indicate liquid volume in either a water or foam tank. This display is capable of providing up to nine separate gradations that are visually displayed as a scrolling light pattern in changing colors, passing from red, to orange, to blue, to green as volume increases. Another example is the KZValve KZCO SL-1, which is a scrolling light type control box used to indicate water valve position, utilizing five LED scroll lights. By movement of a toggle switch connected to a motorized valve, water valve position may be controlled. Water flow is indicated by selectively lighting the scroll lights as flow increases, with up to ten distinct positions between the valve being fully open and fully closed with this device. While this device does provide an easily read display to the operator, it does not address the problem that the degree to which a valve is opened does not necessarily reflect a particular foam quality.
The art also includes at least one attempt to use a scrolling light type display for use specifically with CAFS production. Elkhart Brass Mfg. Co. of Elkhart, Ind. produces an electric valve for CAFS systems under the name ICS (Intelligent CAF Selector). The ICS includes a control panel that allows for push-button switching between CAFS production and water-only mode. It also allows for a “CAF SELECT” mode to toggle between pre-set CAFS discharge settings, i.e., wet, medium, and dry. Although ten LED scrolling lights are used to indicate the degree to which the water valve is open, the only means of adjusting foam quality is by using the “CAFS SELECT” button to toggle between three possible settings, or to choose “water only” by turning CAFS off. The scrolling lights indicate only the degree to which the water valve is open, not the quality of foam being produced.
It may be seen that the scrolling light display systems described above require the use of a motorized, or electric, water valve system. Many CAFS systems, however, use a manually opened or closed water valve. These may be preferred for certain operators due to a lower cost, ease of use, and increased reliability in harsh conditions. Compactness is also an issue, since the space available for equipment and piping on CAFS-equipped firefighting vehicles tends to be quite limited. A system that offered the advantages of a scrolling light display that provided direct feedback about foam quality, and that allowed for such a display in conjunction with a manual water valve, would thus be highly desirable.
Devices or references mentioned in this background section are not admitted to be prior art with respect to the present invention.